Can't access my ViewController Class in prepareForSeque

He!

In my storyboard i have a UINAvigation Controller. The first viewController(A) is embeded into this controller. Then i have a segue to another viewcontroller (B) (i can past data between them by using prepareForSegue). On viewController B i have another button to Segue to the next viewController (C), but i can not pass data to the viewController C, because i can not access to viewControllers C class.
I use following code in my viewController B:

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
  if let foo = segue.destination as? ViewControllerC {
     foo.data = myData
  }
}

But i have no access to ViewControllerC class. I am getting the error: Use of undeclared typ "ViewControllerC"

Is it not possible to pass Data between more than one view in a UINaviationController?
How can i easy pass Data to ViewControllerC?

Many thanks

Build your project first and check your ViewControllerC to see if there's error in it.

Delete these code to see whether you can go to ViewControllerC or not.

Then you can implement the prepare function

I tired what you wrote, but it is still not accessible. So i tried to use a clear generic UIView with an empty ViewController (as C), but i also can not access the C ViewController.
I can access it from A ViewController but not from B.
Maybe there is something other wrong.